Provide ability to validate the inputs to a workflow form beyond the standard single value or regex validations. Something along the lines of the ability to call an external function or API to carry out a check and return a value to confirm allowed value, or writing an inline function to execute and carry out a validation. An example scenario could be checking for existing code repo name when providing a name for a new code repo to be created rather than having this fail at some point later during the pipeline execution.